不知何故，我可以想出如何解决我的问题。长话短说，我会显示我所有的类。简短的免责声明。ChatGPT帮助我解决了这个问题。
我的班级/项目结构：
路径：源代码/main/java/dev/cherry/emp
文件夹"emp"中的树：

.
├── EmpApplication.java
└── Employee
    ├── Controller
    │   └── EmployeeController.java
    ├── Model
    │   ├── Admin.java
    │   └── Clerk.java
    ├── Repository
    │   ├── AdminRepository.java
    │   ├── ClerkRepository.java
    │   └── EmployeeRepository.java
    ├── Service
    │   └── EmployeeService.java
    └── Util
        ├── Employee.java (abstract)
        └── Gender.java (Enum)

以下是一个接一个的课程。抱歉，文字墙：

• • 抽象类员工**

package dev.cherry.emp.Employee.Util;

import jakarta.persistence.*;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

@MappedSuperclass
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
public abstract class Employee {

    @Id
    @Column(name = "emp_id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long empId;
}

• • 班级管理员及文员（分班/儿童班）**

一个二个一个一个

• • 我的存储库类**

package dev.cherry.emp.Employee.Repository;

import dev.cherry.emp.Employee.Util.Employee;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.repository.NoRepositoryBean;

@NoRepositoryBean
public interface EmployeeRepository<T extends Employee> extends JpaRepository<T, Long> {
}

package dev.cherry.emp.Employee.Repository;

import dev.cherry.emp.Employee.Model.Clerk;
import org.springframework.stereotype.Repository;

@Repository
public interface ClerkRepository extends EmployeeRepository<Clerk>{
}

package dev.cherry.emp.Employee.Repository;

import dev.cherry.emp.Employee.Model.Admin;
import org.springframework.stereotype.Repository;

@Repository
public interface AdminRepository extends EmployeeRepository<Admin> {
}

• • 我的服务类**

package dev.cherry.emp.Employee.Service;

import dev.cherry.emp.Employee.Util.Employee;
import dev.cherry.emp.Employee.Model.Admin;
import dev.cherry.emp.Employee.Model.Clerk;
import dev.cherry.emp.Employee.Repository.AdminRepository;
import dev.cherry.emp.Employee.Repository.ClerkRepository;
import lombok.RequiredArgsConstructor;
import org.jetbrains.annotations.NotNull;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
@RequiredArgsConstructor(onConstructor = @__(@Autowired))
public class EmployeeService {
    private final AdminRepository adminRepo;
    private final ClerkRepository clerkRepo;

    public List<? extends Employee> getAllEmps(@NotNull String type) {
        if (type.equals("Clerk")) {
            return (List<Clerk>) clerkRepo.findAll();
        } else if (type.equals("Admin")) {
            return (List<Admin>) adminRepo.findAll();
        } else throw new IllegalArgumentException("Class: " + type + " not found in project");
    }

    public Employee createEmployee(Employee employee) {
        if (employee instanceof Clerk) {
            return clerkRepo.save((Clerk) employee);
        } else if (employee instanceof Admin) {
            return adminRepo.save((Admin) employee);
        } else {
            throw new IllegalArgumentException("Illegal Employee subclass: " + employee.getClass().getSimpleName());
        }
    }

}

• • 我的控制器类**

package dev.cherry.emp.Employee.Controller;

import dev.cherry.emp.Employee.Util.Employee;
import dev.cherry.emp.Employee.Service.EmployeeService;
import lombok.AllArgsConstructor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/employees")
@AllArgsConstructor(onConstructor = @__(@Autowired))
public class EmployeeController {

    private final EmployeeService employeeService;

    @GetMapping(value = "type/{type}")
    public ResponseEntity<List<? extends Employee>> getAllEmps(@PathVariable String type) {
        List<? extends Employee> employees = employeeService.getAllEmps(type);
        return new ResponseEntity<>(employees, HttpStatus.OK);
    }

    @PostMapping("/new")
    public ResponseEntity<Employee> createEmployee(@RequestBody Employee employee) {
        Employee savedEmployee = employeeService.createEmployee(employee);
        return new ResponseEntity<>(savedEmployee, HttpStatus.CREATED);
    }
}

我的代码工程实际上和 Postman 我可以测试我的要求。请随时告诉我一个更好的方式，如果你认为它可以做得更聪明或更少的代码行。
非常感谢您的支持。